Many different types of communication systems have been developed and deployed that utilize digital communication techniques. Digital communication systems, that is, communication systems that utilize digital communication techniques, generally are able to communicate data at higher data rates and with fewer errors than when data is communicated using analog techniques.
Cellular communication systems, for instance, that are now deployed generally make use of digital communication techniques. While used primarily for voice communications, increasingly, the systems are used by which to effectuate data-intensive data services. Text, photographic, and other data files are able to be communicated between communication stations operable in a cellular communication system. Mobile stations, typically of sizes and weights permitting their carriage by users, are used at which to originate or terminate a communication service in which data is communicated. Voice data as well as the aforementioned other types of data, are communicated to, and by, the mobile station operable in such a cellular communication system.
During operation of a cellular communication system in which digital data is communicated, various metrics are used to quantify the quality of the communicated data or of the communication channel upon which the data is communicated. For instance, a bit error rate (BER) is one of such metrics. A bit error rate is a quantification of the number of bit errors, on a time basis, that are introduced into data when the data is communicated upon a communication channel or during its processing once received at a receiver. Large bit error rates are sometimes indicative of poor channel conditions. Whatever the cause, however, a high bit error rate makes the recovery of communicated data more difficult. Compensation can sometimes be made to correct for bit errors in the communicated data. Or sometimes, a data packet or frame that includes too many bit errors is discarded and the data is resent. Quantifications of the bit error rate are used for additional purposes, e.g., to select a modulation scheme and to select when to hand off communications. In some system implementations, when communication conditions are good, a modulation scheme is selected to increase data throughput, and when communication conditions are poor, the modulation scheme is selected to increase the chances of successful communication of the data. And, when used to select when to request a hand off of communications, measurement of increasing bit error rates indicates that a potential hand off of communications would result in an improvement of communications.
Further by way of an example, in a GSM/EDGE (Global System for Mobile Communications/Enhanced Data for GPRS Evolution) cellular communication system, a quantification of the bit error rate, is required to be reported by a mobile station to the network part of the communication system at regular intervals. The bit error rate is used as a received signal quality measurement (RXQUAL). The quantification of the bit error rate is used in the system, e.g., as a means of false alarm reduction for bad speech frames that pass CRC (Cyclic Redundancy Code) comparison.
While various bit error rate estimation schemes are conventionally utilized, the estimation accuracy of such conventional estimators typically exhibit large variance, depending upon, e.g., channel propagation profiles, coding schemes, and equalization types. The BER estimation is sometimes based upon comparisons between known training sequence (TS) values and determinations of received data values. Estimations based on values of the training sequence results in estimations being made upon a relatively small, e.g., 26 symbol-length sequence, resulting in potentially-high estimation variance. That is, the BER estimation is not necessarily reflective of the average bit error rate across an entire burst of data. Other bit error rate estimation schemes exhibit other drawbacks. BER estimation subsequent to channel decoding, based upon SNR-BER (Signal to Noise Ratio-Bit Error Rate) mapping, and other conventional schemes all result in estimations that are problematical under certain communication conditions.
If an improved manner could be provided by which to perform bit error rate estimations, improved communication performance of a communication system would be possible.
It is in light of this background information related to digital communications that the significant improvements of the present invention have evolved.